Control apparatus



L. COOK CONTROL APPARATUS Filed Feb. 10, 194;

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CONTROL APPARATUS Filed Feb. 10, 1941 8 Sheds-Sheet 3 Tag. 3. Z 108 WI08d I089 I08e INVENTOR L 7mm: C 01:

May 11,' 1943. L. COOK CONTROL APPARATUS Filed FQb. 10, 1941 8Sheets-Sheet 4 INVENTOR BY L 7mm: Coo/c firw azzw May 11,1943. 1 L, COCK2,319,114

CQNTROL APPARATUS Filed Feb. 10, 1941 8 Sheets-Sheet 5 v r INVENTOR 50BY Lyman Coo/c rmfr May 11, 1943. L. COOK CONTROL APPARATUS Filed Feb.10, 1941 8 Sheets-Sheet 7 INVENTOR Lyman Coo/u BY 4 I May 11, 1943. 1,cooK 2,319,114

CONTROL APPARATUS Filed Feb. 10, 1941 8 Sheets-Sheet 8 Z6 Z3 25 (r I3 l53 I 5 60 33 I 5 42 70 47 E 7/ I 37 6/ 9 I50 72 Q I48 36111.1: 46 i 4 6664 35% hi ,4?

g g 1 v A 4'. F 1,2 I I Z INVENTOR 7 I L man 6 0/0 Z 4 11W Patented May11, 1943 CONTROL APPARATUS Lyman Cook, Foxboro, Mass., assignor to TheFoxboro Company, Foxboro, Mass., at corporation of MassachusettsApplication February 10, 1941, Serial No. 378,314

15 Claims.

This invention relates to apparatus for varying the value of acontrolled variable condition of a process in accordance with apredetermined time schedule or program.

In industrial processes it is sometimes advantageous to control aprocess in accordance with a time schedule so that, for example, avariable process condition such as temperature is controlled, but thevalue at which it is controlled is shifted in accordance with a timeschedule or program. In some cases, the optimum value or rate of changeof temperature or other process condition to be controlled may vary withthe type of material being processed or with the characteristics desiredin the finished product, or with both. Thus, for example, in the dyeingof cloth,

different heating schedules may be required for difierent types of dyesand for difierent weights and kinds of fabrics. In such cases it may benecessary to make frequent changes in the time temperature schedule usedand apparatus for automatically maintaining such a schedule should ihave operating flexibility, that is, it should be so constructed as tofacilitate changes of schedule.

In one type of controller which has heretofore been used to maintain aschedule, such as time temperature, the value at which the controllerattempts to maintain the process condition, i. e., the set point is setup or down as the case may be according to a time schedule by means of acam. Apparatus of this character is relatively inflexible. The schedulemaintained by such a controller can only be changed by changing the cam,and where many different schedules are used, it is necessary to keep onhand a large stock of cams. The accuracy of the controller, of course,depends upon the accuracy with which the cam surface is cut, and skillis required to cut the cam surface to give desired precision.Furthermore, it may be inconvenient to change from one cam to another.In those cases where adjustable cam type instruments have been used.they have tended to give. less than desired accuracy of control.

The apparatus of the present invention gives improved flexibility andaccuracy. The schedule to be maintained by the controller may be rapidlyand easily changed by making a few simple adjustments and an infinitenumber of different schedules may be obtained. No new cam surfaces needbe cut, and the inconvenience involved in keeping a large stock of camson hand is avoided.

In th present embodiment, the invention is described as applied to theproblem of maintaining a predetermined time temperature schedule and thespecific schedule chosen to illustrate the invention comprises a heatingperiod during which the process temperature may be brought up to apredetermined value, a second heating period of predetermined durationduring which the temperature may be caused to rise at a predeterminedrate, and a third period of predetermined duration during which thetemperature may be maintained constant at a predetermined maximum value.

The many objects and advantages of the present invention may best beappreciated by reference to the accompanying drawings, wherein:

Figure 1 is a front elevation of the exterior of a casing containingapparatus embodying the present invention;

Figure 2 is a composite front elevation of the apparatus with the frontof the casing removed (the following figures are mostly enlargeddetailed views of the mechanism shown in this figure) Figure 3 i a sideelevation taken' along the line 33 of Figure 2 and showing an assemblyconstruction in which time and temperature responsive elements cooperateto operate a pneumatic pilot valve;

Figure 4 is a vertical section taken along line 4-4 of Figure 3 andshowing the connection of the assembly to the time operated part of thecontroller;

Figure 5 is a vertical section taken along line 5-5 of Figure 3 andshowing the connection of the assembly to the starting mechanism;

Figure 6 is a vertical section taken along the line 6-6 of Figure 3 andshowing the connection of the assembly to the temperature responsivemechanism;

Figure 7 is an axial section taken along the line 'i-l of Figure 2 andshowing the main shaft construction Figure 8 is a staggered verticalsection taken along the line 8--3 of Figure 2 and showing certainfeatures of the arc-slotted lever construc-.

tion;-'

Figure 9 is a vertical section along line 9-9 of Figure 7, showing thefront arc-slotted lever and operating arm;

Figure 10 is a vertical section taken along the line Ill-it of Figure 7and showing the back arcslotted lever;

- Figure 11 is a side elevation partly in section Figure 12 is a bottomplan view partly in section of the motor switch mechanism and cut-oil!nozzle taken along line lZ-IZ of Figure 2;-

Figure 13 is a vertical section taken on line I3l3 of Figure 12 andshowing the pneumatic cut-oil. nozzle;

Figure 14 is a vertical section taken on line "-44 of Figure 12 andshowing the motor switch pilot valve;

Figure 15 is a horizontal section taken on line l5-l5 of Figure 2showing the signal lamp and bracket;

Figure 16 is a bottom plan view partly in section of the adjustingmechanism taken on line lG-IG of Figure 2;

Figure 17 is a vertical section taken on line l'l-I'l of Figure 16;

Figure 18 is a vertical section taken on line l8l8 of Figure 16 showingportions of the adjusting mechanism and certain details of the springlever construction; and

Figure 19 is an expanded perspective diagrammatic illustration ofportions of the apparatus.

Referring to the drawings, and more particularly to the lower left-handcomer of Figure 19, there is shown a pneumatically operated controlvalve I which regulates the flow of a heating fluid such as steam in apipe line 2 which supplies a process (not shown). Air to operate thevalve I is supplied to a control head 5 through a pipe 4 from a suitablesource (not shown). The control head 5 regulates the air pressuresupplied to the valve l and comprises a double headed valve 6 mounted ona stem 1 and adapted to cooperate with a supply port 8 communicatingwith'supply line 4 and an exhaust port 9 communicating with atmosphere.Double headed valve 6 is operated by expansion and contraction of abellows l and serves to regulate the air pressure supplied through apipe II to the pneumatically operated control valve I. As the bellows l0expands, the double headed valve moves to the right reducing exhaustport 9 and enlarging supply port 8 to.

increase the pressure in line H and further open control valve I.Similarly, as bellows l0 contracts, the pressure in line I I isdecreased to move the valve I toward closed position. Control head alsoregulates the pressure in line I! connecting line I l with a helicalpressure-responsive element l3.

The interior of bellows l0 communicates through a pipe l4 (see upperpart oi. Figure 19) with a nozzle supported on a tubular bracket l6secured to a hollow collar ll rotatably mounted on a shaft l8. Air issupplied to the pipe l4 (lower part of Figure 19) and nozzle l5 fromsupply line 4 through a branch line l9 containing a restriction 20 whichlimits the flow of air to the nozzle. Thebellows I0 is operated from thepressure in the line l4 back of the nozzle l5. This pressure is variedby means of a flapper 2| which is mounted to oscillate on the shaft l8.Flapper 2| is continuously urged by a light spring 22 against a flapperactuating lever 23 also mounted to oscillate on shaft l8 and pivotallyconnected to diflerential lever 24, the upper end of which is connectedby link 25 to lever 26 of the pressure-- responsive helix [3. The helixl3 cooperates with flapper 2| and nozzle l5 .to operate the control head5 to supply to the helix l3 the proper pressure to maintain the flapperand nozzle in operative relationship. This operative relationship issuch that when the flapper is against the nozzle or is in its closestoperative position with respect to the nozzle, full back pressure existsin the line I 4 and bellows l0 and maximum pressure exists in helix 13;whereas when the flapper moves away from the nozzle beyond a certaindistance, minimum pressure exists in helix l3. The distance throughwhich the flapper moves with respect to the nozzle to bring about theseminimum and maximum pressures is about .001 of an inch. With thisconstruction, the pressure in the helix I3 is maintained sufilcient tokeep the flapper in its operative position with respect to the nozzleand this pressure is the output pressure of the instrument and operatesthe pneumatically operated valve l.

The flapper 2| is also positioned in response to the temperature of theprocess being controlled. Referring to the upper left-hand part ofFigure 19, a temperature-responsive element 3, suitably located tomeasure the temperature of the process, is connected through a flexibletube 21 with a helical temperature-responsive device 28. The element 3,tube 21, and helix 28 form a thermal system of such a character that anincrease in temperature causes the helix 28 to unwind and a decrease intemperature causes it to wind up. The helix is connected by a strip l5|to a rotatable shaft I52 upon which is mounted a lever 29. The operativeconnection between the helix and the lever 29 may be similar to thatdisclosed in Reynolds Patent No. 1,970,819. Lever 29 is connectedthrough link 30 to the lower end of differential lever 24 so that anincrease in temperature tends to move the flapper away from the nozzleand a decrease in temperature tends to move the flapper toward thenozzle.

The mechanism described thus far tends to maintain the temperature ofthe process constant providing no permanent changes in the demand ofprocess are encountered and its operation is as follows: If thetemperature starts increasing above the control value, helix 28 tends tounwind and to move flapper 2i away from the nozzle l5 thereby reducingthe pressure in the pipe l4 and on the bellows ID. This causes theoutput of the control head to decrease, thereby decreasing the pressurein line l2 and in the helix I3. Helix l3 tends to wind up and restorethe flapper to its operating position with respect to the nozzle Hi. Inthis manner the nozzle and flapper under the control of the helix l-3cause the control head to decrease the pressure in the line l2 inproportion to the increase of the temperature. This decrease in thepressure in the line I2 is communicated through the line H to the valveI, causing it to decrease the supply of heat to the process therebycounteracting the condition causing the temperature to increase abovethe control point and thus endeavors to restore the temperature to itsoriginal value. With a decrease in temperature the operation of theparts is reversed.

The temperature maintained by the above described mechanism depends uponthe position of the nozzle l5 and may be varied by turning the nozzleand tubular bracket IS on shaft l8. As pointed out above, theillustrative schedule here used includes an interval during which thetemperature rises at a constant rate followed by an interval duringwhich the temperature is maintained at a constant value. This scheduleis obtained in the present embodiment by moving the nozzle at apredetermined rate for a predetermined interval and then holding thenozzle stationary for a further predetermined interval.

There are three variable factors which determine the characteristics ofsuch a schedule:

(a) the time interval during which the temperature is changed; (1)) thetemperature rise, that is. the final temperature attained relative to afixed initial temperature; and (c) the time interval during which thetemperature is held constant. In the apparatus here described, each ofthese three factors is adjustable to give commercially desirableflexibility.

Mechanism for moving the nozzle |5,will now be described. Referring tothe upper left portion of Figure 19, power to move the nozzle issupplied by a synchronous electric motor 3| which through suitablereduction gearing drives a shaft 32 at a relatively slow constant speedin a clockwise direction as shown. Frictionally connected to the shaft32 there is a clutch disc 34 carrying a lever 33 which, through a link35, is connected to a main operating lever 36 having a time-ofriseindicating arm 36a and a manually adjustable arm 361). Operating lever36 is rotatably mounted on shaft 31 and, to place the mechanism instarting position, is manually moved in a counterclockwise directionuntil arm 36b bears against a stop 38. In the present embodiment, thearm 36b extends through a slot I48 of a casing I50 for housing theapparatus and the upper end of the slot I48 forms the stop 38.

Arm 36b is provided with a depending member 39 which, in the positionshown in Figure 19, intercepts arc-slotted lever 45, also rotatablymounted on shaft 3'! andprovided with an arouate slot 4|. Slidablypivoted at 42a in the slot 4| there is a link 42 which, at its upperend, connects pivotally with a lever 43 fixed to the collar ll of thenozzle mounting. A spring 44 connected to the tubular bracket l6continuously urges the nozzle mounting clockwise and hence urges leverclockwise to bear against member 36 of the operating lever 36. As themotor 3| rotates shaft 32, operating lever 36 is rotated clockwise andarc-slotted lever 46, since it bears against member 39, follows theoperating lever to cause nozzle l5 and its mounting to move at aconstant rate clockwise. As will appear more fully below, the initialcontrol temperature of the mechanism is determined by the position ofthe stop 38.

Clockwise rotation of arc-slotted lever 46 on shaft 3'! is limited by astop on a second arcslotted lever 46, also rotatably mounted on shaft37. When arc-slotted lever 45 meets the stop 45 on arc-slotted lever 46,the operating lever 36 continues to move clockwise, but arc-slottedlever 40 and hence nozzle l5 stop moving. Thus the time during which thenozzle is moving, that is,

the time-of-rise interval, is determined by the distance which thearc-slotted lever 40 travels from its initial position to the pointWhere it meet the stop 45. or in other words, by the initial angularrelationship between arc-slotted lever 40 cating arm 36a is oppositezero on time scale 50.

As stud 41 is rotated clockwise, time scale 50 also moves clockwiseunder the time-of-rise indicating arm 36a and since arc-slotted lever 46is integral with time scale 50, it will be moved to a positioncorresponding to the time which the indicating arm 36a indicates on thetime scale. It is thus apparent that when the indicating arm 36a in itsclockwise movement reaches zero on the time scale, the arc-slotted lever46 will at substantially the same instant meet the stop 45 onarc-slotted lever 46, nozzle I5 will stop moving, and the temperature ofthe process will be maintained constant at a predetermined value.

The total amount the nozzle moves during a particular time-of-riseinterval, and consequently its rate of movement during that interval,may also be adjusted by moving pivot point 42a in slot 4|. As pivotpoint 42a is moved closer to shaft 37, for example, a given movement ofarc-slotted lever 46 will permit less and less movement of the nozzle |5by the spring 44 because the efiective length of arc-slotted lever 40 isreduced. Contrariwise, as the pivot point 42a is moved further fromshaft 31, .a given movement of arc-slotted lever 40 will permit greaterand greater movement of nozzle 5. Hence the position of pivot point 42awith respect to shaft 31 determines the distance the nozzle moves duringa particular time interval and, since operating arm 36b moves at aconstant rate and arc-slotted lever 40 moves with operating arm 36?),this relative position of pivot and shaft also determines the rate atwhich the nozzle moves.

The above-described adjustment is made in the following manner: Locatednear the motor 3| is an adjustment stud 5| having an integral lever 52which is connected to one end of a link 54. A backwardly extending arm53 of lever 52 connects the lever with a second link in such a way thatadjustment of stud 5| moves the two links 54 and 55 conjointly. Link 54is pivotally connected at its other end to link 42 so that rotation ofadjustment stud 5| moves pivot 42a in slot 4|.

As pointed out above, the amount of nozzle movement determines theamount of temperature rise and in order to indicate how far the nozzlewill move or. stated diiierently, what maximum temperature will bereached with respect to a particular initial temperature, there isprovided a temperature scale 56 which is immovable and a movable pointer51. Pointer 51 is a bell crank pivoted at 58 and having an arm 59connected by a link 60 to the arcuate slot 6| of arc-slotted lever 46.Link 55 is pivotally connected to link 60 at 62. Thus. the rotation ofadjustment stud 5| to set the amount of nozzle movement for a given timeinterval also moves pointer 5! to indicate on temperature scale 56 thetemperature which will eventually be reached.

After arc-slotted lever 40 meets stop 45 on areslotted lever 46,operating lever 36 continues moving clockwise until member 39 strikesone end of a cut-off lever 63 which is pivoted at 64 on a bell cranklever 65. Cut-off lever 63 at its other end is connected by a flapperactuating link 66 to a flapper 61 cooperating with a nozzle 68 connectedto the line l4 by a branch line 69. As the operating arm 36 rotates thecut-off lever about its pivot 64, the flapper 61 is drawn a ay fromnozzle 63 and pressure in bellows l0 drops to that of the atmosphere.Hence pressure in line H also becomes equal to atmospheric pressure andthe control valve closes to cut off the steam to the process.

Th:- time-of-hold interval is determined by the time required for theoperating lever 36 to move from the point where arc-slotted lever 40meets stop 45 to the point where member 39of the operating lever strikesthe cut-oil lever 63. This interval may also be adjusted as follows (see.lefthand side of Figure 19) An adjustment stud 10 has an integral leverll connected by a link 12 to the indicating arm 13 of bell crank 85.Rotation of adjustment stud 10 moves bell crank 85 to adjust theposition of cut-ofi lever 83 with respect to operating lever 36, andindicating arm 13 indicates on time scale 50 the magnitude of thetimeof-hold interval.

In practical operation, the temperature of the process at the beginningof a run is frequently below the initial or minimum control temperaturewhich, as described above, is the temperature corresponding to theposition of the nozzle l when arm 36b is in contact with stop 38. Henceit is desirable that mechanism be provided which will permit theinitiation of the cycle of events referred to above only after theprocess has reached this minimum control temperature. In the presentembodiment, this is accomplished by an automatically controlled startingswitch mechanism for starting electric motor 3| when the minimum controltemperature has been reached. The starting switch mechanism comprises ingeneral a pneumatic relay which is made operative at the minimum controltemperature and which actuates a mercury switch to close an electricalcircuit supplying power to the motor. This mechanism will now bedescribed.

Referring now to Figures 3, 5, 6, and 14 of the drawings, andparticularly to Figure 6, the link 30, through an intermediate linkagenot shown in Figure 19, positions the lower end of differential lever 24in accordance with the value of the temperature of the process. As shownin Figure 6, the upper end of link 30 is connected to one arm 14a of aforked lever 14 pivoted at 76a. Pivot 160. (see Figure 3) is located onan arm |08a of a mounting I08 which is fixed to the instrument casingI50. Reverting to Figure 6, the other arm 14b of the forked lever isconnected by the link 15 to the lower end of differential lever 24. Aseries of holes 14c are provided in the arm 14a of the forked lever 14,the function of the holes 14c being to-permit adjustment of theeffective length of lever arm Ila and so of the relationship betweenmovement of link 80 and the lower end of differential lever 2|.

Operatively integral with forked lever II is a U-shaped bracket 16 whichis pivotally supported at one end on arm NM and at its other end on arm|08d of mounting I08. As shown in Figure 5, bracket 18 has an arcuate'arm 11 provided with an arcuate slot 18. A link 18, the upper end ofwhich is slidably secured in slot 18, is at its lower end (Figure 14)connected to arm 80a of a bell crank flapper actuating lever 80rotatably mounted on a shaft 83 which (see Figure 12) is supported in amounting 83a sec'ured to the casing I50. Reverting to Figure 14, arm 80bwhich is operatively integral with am 800 is adapted, through aforwardly projecting lip 80c, to bear against a micrometer adjustingscrew 8|a mounted on a flapper 8| and to move the flapper with respectto a nozzle 82. Flapper 8| is also mounted on shaft 83 and iscontinuously urged toward lip 800 by a light spring 84.

The operation of the mechanism just described is as follows: When thetemperature of the processis below the minimum control temperature ofthe apparatus, bracket 16 is so positioned by thermal element 28 thatthe upper end of link I8 rests against the lower end of slot 18 andflapper 8| is held away from nozzle 82. The flapper is continuouslyurged in a clock wise direction toward nozzle 82 by the force ofgravity. As the temperature of the process increases, bracket IE isrotated clockwise as shown in Figure 5 to permit the flapper to approachthe nozzle, and when the minimum control temperature is reached theflapper covers the nozzle. Thereafter, as bracket 16 continues torotate. the upper end of link (8 slides in slot 18 and there is nofurther relative movement of flapper 8| and nozzle 82 until the end ofthe cycle. The micrometer screw 8|a on flapper 8| permits ad- J'ustmentof the effective length of the link 18 to make the flapper 8| cover thenozzle 82 at the desired temperature value.

Nozzle 82 communicates through a pipe 85 (see Figure 11) with theinterior of a bellows 88 and the pneumatic system thus formed issupplied with air under pressure from a suitable source (not shown).nozzle 82, the pressure behind the nozzle builds up to expand bellows88. A permanent magnet 81 is mounted on an arm 88 secured to the bellows88, and expansion of the bellows moves the magnet closer to a mercuryswitch 88. At its upper end, as shown in Figure 11, bellows 86 isprovided with a relatively stiff spring 80 which tends to preventexpansion of the upper end of the bellows and therefore multipliesexpansion of the lower ended the bellows and so movement of magnet 81.When bellows 86 is expanded, magnet 81 attracts an armature in mercuryswitch 88 to close an electrical circuit (not shown) which supplieselectrical energy to the motor 3|. Thus, when the minimum controltemperature is reached, flapper 8| covers nozzle 82 to expand bellows 88and actuate mercury switch 88 to start the-motor 3|. A signal lamp 8|(see Figure 15) is connected in parallel in the motor circuit toindicate when the apparatus is functioning as a program controller.

When the time-of-hold interval referred to above has elapsed, the motoris automatically stopped. The mechanismfor stopping the motor comprisesin general a linkage actuated by operating lever 38 and operative at theend of the time-of-hold interval to move flapper 8| away from nozzle 82and thus operate mercury switch 88 to interrupt the flow of electricalenergy to the motor. Referring to Figures 2 and 8, operating lever 36(comprising arms 36a and 38b) is provided with a forwardly projectinglip 82 (diagrammatically represented in Figure 19 as tongue 38) which,as the lever rotates clockwise, hits a micrometer screw 83a of a' stop83 on the lower end of lever 83 causing lever 83 to pivot about 64 (seeFigure 2) to move link 88 which is connected to a bell crank flapperactuating lever 8l'rotatably mounted on shaft 83. Referring now toFigure 13, an arm 84a of lever 84 is provided with a forwardlyprojecting lip 84b which bears against a micrometer screw 81a on flapper81 and is adapted to move the flapper with respect to nozzle 68. Theflapper is rotatably mounted onshaft 83 and is urged toward projection84!) by a light spring 88. Fixed to arm 84a is a lever 81 having abackwardly extending arm 88 (best shown in Figure 14) adapted tocooperate with .a micrometer When flapper 8| covers uncovers nozzle 82to stop the electric driving motor. The interval between the actuationof the two flappers may be adjusted by adjusting micrometer screw 99 andis sufilcient to ensure complete closure of control valve I before themotor switch mechanism is operated to stop the electric motor.

The operation of the mechanism -thus far described can be followed ingeneral by reference v to Figure 19. Operating lever 36 is manuallymoved counterclockwise until it meets stop 38, thus moving nozzle I5 toa predetermined initial position. Adjustment stud 41 is then rotated tomove time scale 50 under indicating arm 36a. until the indicating armindicates the desired time-of-rise interval. Adjustment stud 5| isrotated until temperature pointer 51 indicates on temperature scale 56the desired maximum temperature. Adjustment stud I is then rotated tomove indicating arm I3 with respect to time scale 50 until theindicating arm indicates the desired time-of-hold interval. The airsupply to the apparatus is thereafter turned on and, if th processtemperature is below the minimum control temperature of the apparatus,the control valve I will open wide to supply a maximum flow of heatingfluid to the process and the temperature will begin to rise. When theminimum control temperature of the apparatus is reached, flapper 8|(Figures 14 and 11) covers nozzle 82 to operate the mercury switch 8.)to start the electric motor 3| (Figure I9), and operating lever 36 andnozzle [5 start moving clockwise from their zero or neutral position ata constant rate. Arc-slotted lever 40 follows operating lever 36 topermit nozzle I5 to turn about shaft I8 and change the temperature at apredetel'mined and controlled rate until lever 40 reaches stop 45 onarc-slotted lever .46. Nozzle I6 then stops moving and the temperatureis controlled and held at a constant predetermined maximum value whileoperating lever 36 continues to move clockwise. When the operating leverreaches stop 93 on lever 63 (Figures 2 and I9), that lever is rotated tocause flapper 61 to uncover nozzle 66, thereby closing control valveContinued movement of operating lever 36 causes flapper 8| (Figures 14and 11) to uncover nozzle 82, thus opening mercury switch 89 to stop theelectric motor 3| and shut ofi lamp 9| to complete the cycle ofoperation.

Because the successful operation of the abovedescribed apparatus and theimproved results obtainable therewith depend to some extent on thesolution of certain constructional problems, portions of the apparatuswill now be described in somewhat greater detail.

Referring to Figures 2, 8, 9, and 10 of the drawings, and especiallyFigure 9, the manipulating arm 36b of lever 36 forms an acute angle withthe indicating arm 36a. 'I'heforwardly extending lip 92 on arm 36bcooperates with a stop I00 on arc-slotted lever 40. Stop I00 is providedwith a micrometer adjusting screw I 00a to adjust the relationshipbetweenarm 36b and arc-slotted lever 40 in such a way that when arm 36bis against stop 38, the upper pivot point (Figure 2) of link 42'will beat the center of curvature of arcuate slot 4| and movement of pivotpoint 42a in slot 4| will, inthis position of the mechanism, cause nomovement of nozzle I5. Reverting to Figure 9, arc-slotted lever 40 isprovided with a backwardly extending projection or lip |0| adapted tocooperate (Figure 10) with a stop I02 on arc-slotted lever 46 having amicrometer screw I02a. When arc-slotted lever is in its initial orstarting position and lever 46 is so positioned that stop I02 is incontact with lip I0| of lever 40, the screw |02a permits adjustment ofthe relative positions of arc-slotted levers 46 and 40 so that the upperpivot point of link 60 is at the center of curvature of arc 6| andmovement of link 60 by link causes no movement of pointer 51 when theparts are in this position.- Thisrelationship of levers 40 and 46 is notordinarily encountered in practice but the adjustment is desirablyprovided for calibration purposes. The relationship between arcslottedlever 46 and the arm 50a of time scale 50 is made adjustable by amicrometer screw I03.

Referring now to Figures 1. 2, 3, and 4, and particularly'Figure 2, theupper end of link 42 is pivotally connected to nozzle actuating lever 43as described above in connection with Figure 19 and the nozzle assembly,which is supported (see Figure 3) on arms |08e and |08f of mounting I08,is connected by a U-shaped bracket I04 to a pointer I05 which indicatesthe position of the nozzle. Link (Figure 4) at its upper end ispivotally connected to an arm I060 of a U- shaped bracket I06 pivotallymounted at one end on an arm |08b and at its other end (Figure 3) on anarm |08g oi the mounting I08. Secured to the bracket I06 is the pointer51 which indicates the maximum temperature to be attained. Reverting toFigure 4, lateral adjustment of pivot point 60a with respect to pivotpoint I01 01 bracket 06 is obtained by'means of a micrometer screw I06bon arm I06a. This adjustment may be used to adjust the position of pivotpoint 60a with respect. to arcuate slot 6| of arc-slotted lever 46. Alsosecured to bracket I06 is an arm I060 having a forwardly extendingprojection I06d which is adapted to cooperate with the arm |00b to forma stop limit clockwise rotation of arc-slotted lever 46.

Referring now to Figures 2, 3, 5, and 6, and especially Figures 3 and 6,the differential lever 24 is fixed at 24a to ashaft 24b which passesthrough the lever and is rotatably supported at its ends in a U-shapedflapper actuating lever 23 which is itself pivotally mounted at 2312.Flapper actuating lever 23 is provided with a latera1 extension 23awhich (Figure 5) through a micrometer adjusting screw I09, actuatesflapper 2|. A light spring 0 continuously urges flapper 2| against screwI09 of lever 23. Screw I09 serves to adjust the relationship betweenflapper 2| and actuating lever 23, As described above, an increase intemperature causes flapper 2| and bracket 16 to rotate clockwise, asshown, and a decrease in temperature causes the flapper and bracket torotate counterclockwise. Supported on the bracket 16 at its left-handend as'shown in Figure 3 there is a pointer I II which indicates thetemperature of the process. After the temperature of the process reachesthe minimum control temperature of the apparatus, pointer I and pointerI05 will substantially coincide for the remainder of the cycle; and whenthe temperature of the process reaches its predetermined maximum value,the three pointers 51, I05, and III will substantially coincide for theremainder of the cycle.

to the casing I50. .The three shafts are provided at their upper endswith squared portions which have heretofore been referred to,respectively, as adjustment stud 10, adjustment stud 41 and adjustmentstud I. Figure 16) is a pinion IIB which engages a gear II1 rotatablysupported on mounting I15 and fixed (see Figure 2) to arm 1I. Rotationof stud rotates pinion I I6, gear I I1 and arm H to move link 12 whichis pivotally connected at its righthand end to a triangular plate II8rotatably mounted on shaft 31. The pivot 84 of cut-off lever 53 and thetime-of-hold indicating arm 13 are fixed upon plate I I8 and thusadjustment of stud 10 adjusts the position of the cut-off lever andmoves indicating arm 13 to such a position as to indicate the magnitudeof the time-of-hold interval.

Referring again to Figures 16 and 1'1, shaft H3 is provided with apinion II8 which engages a gear I20 rotatably supported on mounting I I5and fixed (see Figure 18) to arm 48. Rotation of adjustment stud 41rotates arm 48 to move link 49 which, as shown in Figure 10, rotatesarc-slotted lever 45 and time scale arm 50a on shaft 31. Reverting toFigure 16, shaft H4 is similarly provided with a pinion I2I whichengages a gear I22 rigidly secured to arm 52 in such a manner thatrotation of stud 5I through arm 52 moves link 55 (see Figure 19) to settemperature limit indicator 51.

In order to prevent injury to the parts due to over-adjustment of theadjustment studs, certain of the links, including links 54 and 55operated by adjustment stud 5I, and link 80 operated by adjustment stud41, are provided with a safety device such as the sliding connection I23shown Secured to shaft II2 (see in Figure 18. Sliding connection I23comprises a sleeve I24 of link 54 which receives the end of a shank I25of link 54. The shank I25 is provided with a button I25 which isslidably fitted to the interior surface of sleeve I24 and which normallybears against a shoulder I24a of sleeve I24. Button I28 operates againstan internal spring I28 which at its right-hand end bears against awasher I21 held in place by a turned-in lip I241) of the sleeve I24.Spring I28 permits elongation of link 54 if the link is subjected tomore than ordinary tension while the parts are being adjusted in themanner described above.

Referring now to Figure 8, links 54 and provided respectively with yokesI28 and I30 which fit over the double pivots I3I and I32, securedrespectively to links 42 and 80. Link 42 is provided with a yoke I33having downwardly extending arms I33a and I33b which embrace arc-slottedlever 40. At their lower ends, arms I33a and I331; are provided with aroller I34 which fits into the arcuate slot M of arc-slotted lever 48and facilitates movement of pivot point 42a in the slot. Link 80 isprovided with a similar yoke I35 and roller I35.

of the main shaft 31 which is supported in a mounting I31 secured to theinstrument casing I50. A cylindrical rod I38 having hemispherical endsis mounted at its right-hand end in a rigid thrust bearing I38 and atits left-hand end is provided with a shoulder I38a which bears against abushing I40 fixed. to the mounting I31. The time-of-hold indicating arm13 is rotatably mounted on bushing I48 and is urged against an annularshoulder I40a of the bushing I40 by a spring washer I4I interposedbetween the arm .13 and the mounting I31. The operating lever 35 are Iincluding the indicating arm 36a is fixed to a disc I42 integral withthe rod I38. For most of its length the rod I38 is embraced by a sleeveor bushing I43 which is fixed to'and supports areslotted lever 40. Aportion of rod I38 withinthe bushing I43 is reduced in diameter as atI44 to decrease friction between the rod and bushing. At its right-handend the bushing I43 bears against the thrust bearing I33 and at itslefthand end the bushing bears against a shoulder I381) of the rod I38.Arc-slotted lever 40 and bushing I43 are rotatable both with respect tothe rod I38 and with respect to the mounting I31. Arc-slotted lever 46and time scale 50 are rotatably mounted on a third bushing I45 which isfixed to mounting I31. A spring washer I45 urges lever 48 and arm 50a oftime scale 50 against a shoulder 511 of bushing I45 in such manner thatthe lever and time scale are rotatable with respect to mounting I31.Thus, with the construction shown, arc-slotted levers 40 and 46,operating lever 36, and time-of-hold indicating arm 13 are independentlyrotatable in such manher that there is no undesirable looseness of theirrespective bearings.

From the above description it is apparent that the present inventionprovides an apparatus readily adjustable to control the variation of aprocess condition, such as temperature, in accordance with a relativelybroad selection of predetermined time schedules. Changes may be madefrom schedule to schedule with comparative ease bymaking a few simpleadjustments. It is, of course, to be understood that the abovedescription refers to a specific embodiment of the invention and thescope of the invention is to be determined from the claims appendedhereto.

I claim:

1. In control apparatus for maintaining the position of a movableelement in correspondence with a predetermined but adjustable timeschedule, the combination of a movable member, means for-moving saidmember at constant speed, means interconnecting said member and saidelement for causing said element to move from a zero position withmovement of said member, said interconnecting means being adjustable tovary the rate at which said element moves with respect to the rate ofmovement of said member, and stop means for stopping the movement ofsaid element at the end of a predetermined interval of time after saidelement starts moving from said zero position, said stop means beingadjustable independently of said interconnecting means and said memberto adjust the length of said interval of time. D

2. In control apparatus for maintaining the position of a movableelement in correspondence with a predetermined but adjustable timeschedule, the combination of a movable member, means for moving saidmember at constant speed, means interconnecting said member and saidelement for causing said element to move with movement of said member,said interconnecting means being adjustable to vary the rate at whichsaid element moves with respect to the rate of movement of said member,first stop means for stopping the movement of said element apredetermined interval oi. time after the initial movement of saidmember, and second stop means for stopping the movement of said member apredetermined interval of time after the stopping of said element. saidfirst stop means and second stop means being adjustable independently ofsaid interconnecting ea s a pendently of one another to adjust thelengths of said intervals of time.

3. In control apparatus for maintaining the position of a movableelement in correspondence with a predetermined but adjustable timeschedule, the combination of a movable member, means for moving saidmember at constant speed, means interconnecting said member and saidelement for causing said element to move with movement of said member,said interconnecting means being adjustable to vary the rate at whichsaid element moves with respect to the rate of movement of said member,indicating means adjustable conjointly with adjustment of saidinterconnecting means to indicate the final position to be attained bysaid element, and stop means for stopping the movement of said element apredetermined interval of time after the initial movement of saidelement, said stop means being adjustable independently of saidinterconnecting means and said member to adjust the length of said timeinterval.

4. In control apparatus for maintaining the position of a movableelement in correspondence with a predetermined but adjustable timeschedule, the combination of a movable member, means for moving saidmember at a constant speed from an initial neutral position, means fordetermining the initial neutral position of said member, meansinterconnecting said member and said element for causing said element tomove with movement of said member, said interconnecting means beingadjustable to vary the rate at which said element moves with movement ofsaid member and stop means for stopping the movement of said element apredetermined interval of time after the initial movement of saidmember, said stop means being adjustable independently of saidinterconnecting means and said member to adjust the length of said timeinterval.

5. In control apparatus for maintaining the position of a movableelement in correspondence with a predetermined but adjustable timeschedule, the combination of a movable member, means for moving saidmember at constant speed, means interconnecting said member and saidelement for causing said element to move with movement of said member,said interconnecting means being adjustable to vary the rate at whichsaid element moves with respect to the rate of movement of said member,stop means for stopping the'movement of said element a predeterminedinterval of time after the'initial movement of said member, said stopmeans being adjustable independently of said interconnecting means andsaid member to adjust the length of said time interval, and indicatingmeans adjustable conjointly with adjustment of said stop means forindicating the magnitude of said time interval.

6. In control apparatus for maintaining the position of a movableelement in correspondence with a predetermined but adjustable timeschedule, the combination of a movable member, means for moving saidmember at constant speed, means interconnecting said membenand saidelement for causing said element to move withmovement of said member,said interconnecting means being adjustable to vary the rate at whichsaid element moves with respect to the rate of movement of said member,first stop means for stopping the movement of said element apredetermined interval of time after the initial movement of saidmember, said first stop means being adjustable independently of saidinterconnecting means and said member to adjust the length of said timetion of a movable element in correspondence with a predetermined butadjustable time schedule, the combination of a member adapted to berotated at constant speed, motor means for driving said member, meansmechanically interconnecting said member and said element for causingsaid element to move with movement of said member, said interconnectingmeans being adjustable to vary the rate at which said element moves withrespect to the rate of movement of said member,

means for energizing said motor means to cause said member to rotate,and means for deenergizing said motor means a predetermined interval oftime after said motor means is energized to cause said member to stoprotating.

8. In a controller for controlling the value of a condition byregulating a controlled variable affecting the value of said conditionin response to the value of said condition and in response to time, thecombination of control means for regulating said controlled variable,condition-responsive means responsive to the value of said condition foroperating said control means, and timeresponsive mechanism for operatingsaid control means conjointly with said condition-responsive means, saidtime-responsive mechanism comprising a movable element for operatingsaid control means, a movable member, means for moving said member atconstant speed, means interconnecting said member and said element forcausing said element to move with movement of said member, saidinterconnecting means being adjustable to vary the rate at which saidelement moves with movement of said member, and stop means for stoppingthe movement of said element a predetermined interval of time after theinitial movement of said member said stop means being adjustableindependently of said interconnecting means and said member to adjustthe length of said period of time.

9. In a controller for controlling the value of a condition byregulating a controlled variable affecting the value of said conditionin response to the value of said condition and in response to time, thecombination of control means for regulating said controlled variable,condition-responsive means responsive to the value of said condition foroperating said control means, and timeresponsive mechanism for operatingsaid control means conjointly with said condition-responsive means, saidtime-responsive mechanism comprising a movable element for operatingsaid control means, a movable member, means for moving said member atconstant speed, means interconnecting said member and said element forcausing said element to move with movement of. said member, saidinterconnecting means being adjustable to vary the rate at which saidelement moves with movement or said member, indicating means adjustableconjointly with adjustment 'of said interconnecting means for indicatingthe maximum value to be attained by said condition, and stop means forstopping the movement of said element a predetermined interval of timeafter the initial movement of said member, said stop means beingadjustable independently of said interconnecting means and said memberto adjust the length of said time interval.

10. In a controller for controlling the value of a condition byregulating a controlled variable affecting the value of said'conditionin response to the value of said condition and in response to time, thecombination of control means for regu-- lating said controlled variable,condition-responsive means responsive to the value of said condition foroperating said control means, and timeresponsive mechanism for operatingsaid control means conjointly with said condition-responsive means, saidtime-responsive mechanism comprising a movable element for operatingsaid control means, a rotatable member, means for rotating said memberat constant speed from an initial neutral position, means for initiatingmovement of said member at a predetermined value of said condition,means mechanically interconnecting said member and said element forcausing said element to move with movement of said member, saidinterconnecting means being adjustable to vary the rate at which saidelement moves with movement of said member, and stop means for stoppingthe movement of said element a predetermined interval of time after theinitial movement of said member, said stop means being adjustableindependently of said interconnecting means and said member to adjustthe length of said time interval.

11. In a controller for controlling the value of a condition byregulating a controlled variable afiecting'the value of said conditionin response to the value of said condition and in response to time, thecombination of control means for regulating said controlled variable,conditionresponsive means responsive to the value of said condition foroperating said control means, and time-responsive mechanism foroperating said control means conjointly with said conditionresponsivemeans, said time-responsive mechanism comprising a movable element foroperating 'said' control means, a member adapted to be rotated at aconstant speed from an initial neutral position, motor means for drivingsaid member, means for energizing said motor means at a predeterminedvalue of said condition,

means mechanically interconnecting said mamher and said element forcausing said element to move with movement of said member, saidinterconnecting means being adjustable to vary the rate at which saidelement moves with movement of said member, stop means for stopping themovement of said element a predetermined interval of time after theinitial movement of said member, and means for deenergizing said motormeans a predetermined interval of time aftersaid motor means isenergized.

12. In a controller for controlling the value of a condition byregulating a controlled variable affecting the value of said conditionin response to the value of said condition and in response to time, thecombination of control 'means for regulating said controlled variable,conditionresponsive means responsive to the value of said condition foroperating said control means, and time-responsive mechanism foroperating said control means conjointly with said cnditl0n responsivemeans, said time-responsive mechanism comprising a movable element foroperating said control means, a member adapted to be rotated at aconstant speed from an initial neutral position, motor means for drivingsaid member, control mechanism operated by. said condition-responsivemeans for energizing said motor means at a predetermined value of saidcondition, means mechanically interconnecting said member and saidelement for causing said element to move with movement of said member,said interconnecting means being adjustable to vary the rate at whichsaid element moves with movement of said member, stop means for stoppingthe movement of said element a predeterminedinterval of time after theinitial movement of said member, and time-responsive means fordeenergizing said motor means a-predetermined interval of time aftersaid motor means is energized.

13. In control apparatus for maintaining the position of a;movableelement in correspondence witha predetermined but adjustable timeschedule, the combination of a slotted lever means for rotating saidlever at a constant speed, a link operatively conected to said movableelement and slidably connectedin the slot of said lever for causing saidelement to move with movement of said lever, and means for adjustings'aid link in said slot to vary the rate at which said element moveswith said lever, said adjusting means including an adjustment stud andspring means to prevent injury of said link due to overadjustment.

14. In control apparatus for maintaining the position of a movableelement in-correspondence with a predetermined but adjustable timeschedule, the combination of a first slotted lever means for rotatingsaid .lever about an axis at a constant speed, a link operativelyconnected to said movable element and slidably connected to the slot ofsaid slotted lever for causing said element to move with movement ofsaid lever, means for adjusting said link in said slot to vary the rateat which said element moves with said lever, and means adjustableconjointly with said last-mentioned adjusting means for indicating thefinal position of said element, said conjointly adjustable meansincluding a second slotted lever coaxial with said first slotted lever,an indicator, and a link operatively connected to said indicator andslidably connected in the slot of said second slotted lever.

15. In apparatus for controlling the value of a condition of a processin accordance with a predetermined schedule, in combination, a pneu-"matic couple comprising a flapper and nozzle,

means responsive to the value of said condition for relatively movingsaid flapper and nozzle, time-responsive means for relatively movingsaid nozzle and flapper including a constant speed I of said conditionreaches a predetermined mag-- nitude, and means for deenergizing saidmotor a predetermined interval of time after said motor is energized.

LYMAN COOK.

